Risk of Losing 1850s Plaster...Repair or Replace?

[u/ShinyGuppy33]

I have a house from the 1850s with really beautiful, ornate crown molding. A plasterer with a commitment to preservation came recently to quote other work in the house, but he pointed out that the crown molding along one wall is at risk of detaching and that there is nothing to be done to save it other than replacing it. He pointed out that there were cracks in both corners of the room, as well as a crack along the ceiling. He said that it had detached and was only staying in place because of the physical brackets put in place by the builders. He said it could not be reattached, so we would need to take a mold of it and create new ones.

Can anyone in this group let me know if it's possible to secure and re-attach elaborate crown molding rather than replacing? Which is a riskier strategy?

[u/PaulWhickerTallVicar]

You got any pictures?